1. Field
The following description relates to a multiple input multiple output (MIMO) communication system, a codebook and a method of adaptably transforming the codebook.
2. Description of the Related Art
Studies are being conducted on various types of multimedia services such as voice services that can support high quality and high speed data transmission in a wireless communication environment. Technologies associated with a multiple input multiple output (MIMO) communication system using multiple channels in a spatial area are in rapid development.
In a MIMO communication system, a base station and terminals may use a codebook. A particular space may be quantized into a plurality of vectors or matrices. The plurality of vectors and/or matrices that are generated by quantizing the particular space may be stored in the base station and the terminals as the codebook.
For example, a terminal may select any one codeword from a plurality of codewords included in the codebook. The selected codeword may be based on a channel that is formed between the base station and the terminal. The base station may also recognize the selected codeword based on the codebook. The selected codeword may be used as a beamforming vector to generate a transmission signal between the base station and the terminal.
The design of a codebook is an important issue in the MIMO communication system. For example, it may be effective to design the codebook to be consistent with a variable channel environment. In particular, even in an environment where there is some constraint on a number of feedback bits, it is possible to enhance a throughput of the MIMO communication system, and to decrease a quantization error using a codebook.